For me yes. Tolkien offers several descriptions of the sort of characteristics which would differentiate maiar orcs from other orcs. Actually of all the orcs we know of Azog would be pretty near the top of the list of likely candidates, for me. So I find this a very interesting idea, although of course it is on,unnecessary of several possibilities.

As I say, it is a perfectly respectable position to take to say that the act of publishing confers primacy on a particular work (although it might be a shame to take too hard a line on that here as it would rather rule out the Sil). It also raises interesting clashes such as Treebeard's comment on Orc origins in LOTR vs Tolkien's specific refutation of those comments in his letters, the first being published by him and the second not, of course.

I think it is less easy to understand your points which seem to build to the suggestion that anything not in the form of a story can be safely ignored. I don't think this makes sense to me and if we tried a little experiment where I told you that the essays I mentioned started with the words "I once met a wizard who asked me for my thoughts....." I would be surprised if you felt that was sufficient reason to dramatically alter your views on the validity of what followed.

I think equally the notions of abandoned fragments which somehow didn't make it into practice is also not a notion I share. This would rule us out from considering almost everything he wrote, the Sil included, and I think there is much interest to be had.

Equally, whilst it is a viewpoint, I would tend to disagree with the notion that when you adapt the hobbit, as full an appreciation of the wider contexts of Tolkien's work as possible is not a good thing. To use your Silmarillion example I would tend to argue that it was just such a wider knowledge which enabled CT to pull the work together, rather than the absence of it.